Clean air is a fundamental requirement for the well-being of all living organisms on Earth. It is essential for human health, environmental sustainability, and overall quality of life. This report provides an overview of the state of clean air in some countries, highlighting key issues, challenges, and the progress made in ensuring breathable air for everyone. 

The Air Quality Index (AQI) is a common metric used to assess air quality. It ranks air quality on a scale from 0 to 500, with higher values indicating worse air quality. In many parts of the world, AQI values often exceed recommended safe levels, leading to adverse health effects.

Progress: China's air quality continues to show year by year improvement. Nearly 64 percent of cities demonstrated reductions in their annual PM2.5 concentrations. This resulted in a slight decrease of China's annual PM2.5 concentrations from 32.6 µg/m³ in 2021 to 30.6 ug/m in 2022. While all the most populated Chinese cities featured in this report have seen improving PM2.5 levels with reductions ranging from a five percent (Chengdu) to 16 percent (Chongqing), none of the cities in the country have met the WHO annual guideline of 5 µg/m³.

Challenges: China's coal usage continues to be a point of concern. China is responsible for a large portion of the world's coal production and usage." Coal combustion is a significant contributor to the country's PM2.5 emissions profile along with other sources such as industry, biomass burning, road dust, and road vehicles. In order to combat these issues, China announced a new emissions reporting framework in 2022 to hold companies and industries accountable for the pollution they release¹³.

Progress: South Korea continues the trend of PM2.5 concentration reductions with an annual concentration of 18.3 µg/m³ in 2022 down from 19.1 µg/m³ in 2021. This includes reductions in the key cities of Seoul, Busan, and Daegu. The capital city Seoul, which is the most populous in the country, saw a reduction in PM2.5 concentrations of 7.1 percent from last year and 27.3 percent since 2017. Incheon, Ulsan, and Daejeon however, suffered small increases in their annual average concentrations. Although no city in South Korea met the WHO annual concentration guideline of 5 ug/m or less, the monthly concentrations in some cities fell below 5.0 µg/m³ in July. The country as a whole saw PM2.5 concentrations reduced in 55 of the 98 total cities included in the report.

Challenges: South Korea faces pollution from areas of manufacturing, industrial sites, sand and dust storms from the Gobi Desert, and high traffic pollution from big cities. The geography of the nation, the proximity to deserts, and increased frequency of dust storms due to climate change come together to bring fine dust to many parts of the country. These combined threats to air quality require careful consideration and specialized plans to reduce the health impact for people in South Korea.

Progress: India's annual average PM2.5 level in 2022 was 53.3 µg/m³, only slightly lower than the 2021 average of 58.1, In 2021, 12 of the 15 most polluted cities in the Central and South Asia were in India. That number stayed the same in 2022. Two of the top 15 most polluted cities in the region, Darbhanga and Asopur, deployed government stations in 2022. Bhiwadi, the most polluted city in the country, saw annual PM2.5 levels of 92.7 µg/m³, and roughly 60 percent of cities in India included in this report experienced annual PM2.5 levels of at least seven times higher than the WHO guideline.

Challenges: Air pollution is the second biggest risk factor for disease based on the 2019 Global Burden of Disease report, and the economic cost of air pollution is estimated to exceed $150 billion dollars annually. The transportation sector's contribution to PM2.5 varies from 20-35 percent across Indian cities. The National Clean Air Program (NCAP), launched by the Indian government in 2019, was updated in 2022 with a new target of 40 percent reduction in PM concentration by 2026. The plan seeks to reduce PM concentrations by 20-30 percent by 2024 in all identified non-attainment cities, increase air quality monitoring, and conduct source apportionment studies.

Stubble (crop) burning is also an important challenge in the region but is an episodic phenomenon confined to few areas, including Delhi and North India. In 2022, India relaxed environmental compliance rules for coal mines which allowed for increased production in response to power outages exacerbated by extreme heatwaves. In November, steam coal/thermal coal imports hit a ten month low and total coal production increased 11.7 percent to 75.9 million tons.47,48.

progress: Indonesia's air quality improved in 2022, with an annual average PM2.5 concentration of 30.4 ug/m marking an 11 percent decrease from 2021. Jakarta improved its PM2.5 concentration for the third year in a row, with a 7.7 percent decrease since 2021 and a 27 percent decrease since 2019. The city's annual average PM2.5 concentration was 36.2 ug/m³ in 2022. Citizens in Jakarta and other major cities are especially vulnerable to air pollution from vehicle emissions and high-congestion traffic areas. Four cities in Indonesia satisfied the WHO PM2.5 concentration recommendations, accounting for ten percent of cities that provided adequate air quality information for the year. The two new cities represented in this year's report are also the two most polluted: Pasarkemis and Cileungsir recorded average PM2.5 concentrations of 49.6 µg/m and 36.6 µg/m³, respectively.

Challenges: Air pollution in Indonesia is driven by coal-fired power plants, forest fires, and peatland degradation, while major cities are especially impacted by vehicle emissions, Indonesia is still developing sustainable infrastructure to mitigate airborne pollutants from these sources. Recent regulatory actions include setting stricter standards on vehicle emissions, programs to improve residential stoves, and making landowners and corporations responsible for fires that occur on their land.

Poor air quality is linked to a range of health problems, including respiratory diseases, cardiovascular issues, and premature deaths. Vulnerable populations, such as children, the elderly, and those with pre-existing health conditions, are at higher risk.

• Reduce Emissions: Countries and industries should strive to reduce emissions from sources such as vehicles, factories, and power plants. This can be achieved through cleaner energy sources, stricter regulations, and the adoption of sustainable practices.
• promote clean energy: Transitioning to renewable energy sources like solar, wind, and hydroelectric power can significantly reduce air pollution and greenhouse gas emissions.
• Public Transportation: Encouraging the use of public transportation and promoting electric vehicles can help reduce emissions from the transportation sector.
• Reforestation: Planting trees and preserving forests helps absorb carbon dioxide and improve air quality.